Aluminum-manganese alloys containing up to about 1.5% by weight manganese are widely used for the manufacture of rolling stock and aluminum-manganese alloys containing in excess of about 1.5% and up to about 10.0% by weight of manganese are employed as master alloys for the preparation of manganese containing aluminum alloys, for example Al-Mn-Si and Al-Mn-Mg. Preparation of aluminum-manganese alloys in the past has generally been accomplished by incorporation of highly pure manganese in molten aluminum. This procedure requires highly pure manganese metal and as manganese is usually made by either blast furnace beneficiation of manganese containing ores or from ferromanganese alloys, the manganese metal resulting from these processes must be purified to render it suitable as an alloying element for aluminum. Impurities, which are extremely hard to remove from manganese metal, include carbon and iron and it is known that these impurities, when incorporated in aluminum may impart undesirable properties to the alloy. Consequently, in order to avoid introduction of unwanted impurities into the aluminum-manganese alloy, the manganese must be subjected to extensive and expensive purification processes.
It has now been discovered that aluminum-manganese alloys containing up to about 9% by weight manganese can be readily and efficiently prepared from oxides of manganese rather than from manganese metal. The novel method eliminates the need for making high purity manganese metal and allows the preparation of aluminum-manganese alloys having controlled manganese content and high purity.